diff --git a/src/emacs/lean-debug.el b/src/emacs/lean-debug.el
index c5863821d6..753c24065e 100644
--- a/src/emacs/lean-debug.el
+++ b/src/emacs/lean-debug.el
@@ -5,7 +5,6 @@
 ;;
 (require 'cl-lib)
 
-(defvar lean-debug-mode        nil)
 (defvar lean-debug-buffer-name "*lean-debug*")
 
 (defun lean-turn-on-debug-mode (&optional print-msg)
@@ -47,4 +46,25 @@
                              (cons (propertize time-str 'face 'font-lock-keyword-face)
                                    args)))))
 
+(defun lean-debug-mode-line-status-text ()
+  "Get a text describing STATUS for use in the mode line."
+  (let ((text
+               ;; No Process : "X"
+         (cond ((not (lean-server-process-exist-p))
+                "X")
+               ;; Number of Async Queue: *-n
+               ((> (lean-server-async-task-queue-len) 0)
+                (format "*-%d" (lean-server-async-task-queue-len)))
+               ;; Async Queue = 0
+               (t ""))))
+    (concat " LeanDebug" text)))
+
+(define-minor-mode lean-debug-mode
+  "Minor mode for lean debugging."
+
+  :init-value nil
+  :lighter lean-debug-mode-line
+  :group 'lean
+  :require 'lean)
+
 (provide 'lean-debug)
diff --git a/src/emacs/lean-settings.el b/src/emacs/lean-settings.el
index 7d565bef83..718585d302 100644
--- a/src/emacs/lean-settings.el
+++ b/src/emacs/lean-settings.el
@@ -109,4 +109,10 @@ written."
                  ;;(const :tag "Only Beyond lean-rule-column" lines-tail)
                  ))
 
+(defcustom lean-debug-mode-line '(:eval (lean-debug-mode-line-status-text))
+  "Mode line lighter for Lean debug mode."
+  :group 'lean
+  :type 'sexp
+  :risky t)
+
 (provide 'lean-settings)